Why Brining Keeps Meat
So Moist
A food scientist explains how
a soak in a salt solution makes lean meat juicier and more flavorful
Roasted turkey breast, sautéed pork chops, and stir-fried shrimp all tend to
suffer a common fate when they're cooked even a few minutes longer than
necessary: they get dry and tough. Actually, any kind of meat or fish will taste
like shoe leather if it's severely overcooked, but turkey, pork, and shrimp are
particularly vulnerable because they're so lean. Luckily, there's a simple
solution (literally) for this problem. Soaking these types of leaner meats in a
brine -- a solution of salt and water -- will help ensure moister, juicier
results.
How a brine works
Moisture loss is
inevitable when you cook any type of muscle fiber. Heat causes raw individual
coiled proteins in the fibers to unwind -- the technical term is denature -- and
then join together with one another, resulting in some shrinkage and moisture
loss. (By the way, acids, salt, and even air can have the same denaturing effect
on proteins as heat.) Normally, meat loses about 30 percent of its weight during
cooking. But if you soak the meat in a brine first, you can reduce this moisture
loss during cooking to as little as 15 percent, according to Dr. Estes Reynolds,
a brining expert at the University of Georgia.
Brining enhances juiciness in several ways. First of all, muscle fibers simply
absorb liquid during the brining period. Some of this liquid gets lost during
cooking, but since the meat is in a sense more juicy at the start of cooking, it
ends up juicier. We can verify that brined meat and fish absorb liquid by
weighing them before and after brining. Brined meats typically weigh six to
eight percent more than they did before brining -- clear proof of the water
uptake.
Another way that brining increases juiciness is by dissolving some proteins. A
mild salt solution can actually dissolve some of the proteins in muscle fibers,
turning them from solid to liquid.
Of all the processes at work during brining, the most significant is salt's
ability to denature proteins.
The dissolved salt causes some of the proteins in muscle
fibers to unwind and swell. As they unwind, the bonds that had held the protein
unit together as a bundle break. Water from the brine binds directly to these
proteins, but even more important, water gets trapped between these proteins
when the meat cooks and the proteins bind together. Some of this would happen
anyway just during cooking, but the brine unwinds more proteins and exposes more
bonding sites. As long as you don't overcook the meat, which would cause protein
bonds to tighten and squeeze out a lot of the trapped liquid, these natural
juices will be retained.
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Brining basics:
How long to brine
depends on the size and type of meat you've got. Larger meats like a whole
turkey require much more time for the brine to do its thing. Small pieces of
seafood like shrimp shouldn't sit in a brine for more than half an hour. In
fact, any meat that's brined for too long will dry out and start to taste salty
as the salt ends up pulling liquid out of the muscle fibers. (Be sure not to
brine meats that have already been brined before you buy them, such as
"extra-tender" pork, which has been treated with sodium phosphate and water to
make it juicier.)
It's vital to have a brine with the correct salt concentration,
especially for lengthy brining
times. Small, thin pieces of meat like fish fillets or shrimp can withstand a
concentrated brine because they'll be immersed for only half an hour or less.
But for longer brines, Dr. Reynolds suggests using 9.6 ounces of salt for every
gallon of water. One scant cup of table salt per gallon of water would put you
within range.
If you're using kosher salt, you'll need to use more of it by volume.
This is because kosher salt
has larger crystals and is bulkier than table salt. I actually prefer using
kosher salt in brines because it dissolves much faster, and it comes in nice big
cartons. Using Diamond Crystal kosher salt, you'll need 2 cups per gallon of
liquid. Morton's kosher salt is denser, and you only need 1-1/3 to 1-1/2 cups
per gallon of liquid to get the brine concentration that Dr. Reynolds
recommends.
Any food-safe nonreactive container is fine for brining. For brining turkeys, I
use a plastic turkey cooking bag that will completely enclose the turkey; the
meat needs to be completely submerged. I put the turkey in the bag and then set
the whole thing in a large bowl. I add water to the bag with a measuring cup,
keeping track of how much I've added. Then I add the correct amount of salt. If
I'm brining a familiar turkey size and I know the approximate amount of salt, I
just rub the salt directly on the turkey, inside and out, before adding the
water. I put the bowl in the refrigerator (all meats should be refrigerated
during brining) and let the meat soak for 12 to 24 hours. Discard the brine
after use; for safety reasons, it should never be reused. (For a slightly
different approach, see
How to brine your Thanksgiving bird.)
Whatever you're brining, remember to rinse the meat or fish well afterward to
remove any surface salt. Properly brined meat shouldn't taste salty, just very
juicy with good flavor. But do reduce the amount of salt called for in the
recipe; that is, don't add salt until the dish is at a point where you can taste
it and judge.